Oxidative stress induced-neurodegenerative diseases: the need for antioxidants that penetrate the blood brain barrier

Oxidative stress (OS) has been implicated in the pathophysiology of many ne urological, particularly neurodegenerative diseases. OS can cause cellular damage and subsequent cell death because the reactive oxygen species (ROS) oxidize vital cellular components such as lipids, proteins, and DNA. Moreov er, the brain is exposed throughout life to excitatory amino acids (such as glutamate), whose metabolism produces ROS, thereby promoting excitotoxicit y. Antioxidant defense mechanisms include removal of O-2, scavenging of rea ctive oxygen/nitrogen species or their precursors, inhibition of ROS format ion, binding of metal ions needed for the catalysis of ROS generation and u p-regulation of endogenous antioxidant defenses. However, since our endogen ous antioxidant defenses are not always completely effective, and since exp osure to damaging environmental factors is increasing, it seems reasonable to propose that exogenous antioxidants could be very effective in diminishi ng the cumulative effects of oxidative damage. Antioxidants of widely varyi ng chemical structures have been investigated as potential therapeutic agen ts. However, the therapeutic use of most of these compounds is limited sinc e they do not cross the blood brain barrier (BBB). Although a few of them h ave shown limited efficiency in animal models or in small clinical studies, none of the currently available antioxidants have proven efficacious in a large-scale controlled study. Therefore, any novel antioxidant molecules de signed as potential neuroprotective treatment in acute or chronic neurologi cal disorders should have the mandatory prerequisite that they can cross th e BBB alter systemic administration. (C) 2001 Elsevier Science Ltd. All rig hts reserved.